% Script postProcessing.m processes the raw signal from the specified data
% file (in settings) operating on blocks of 37 seconds of data.
%
% First it runs acquisition code identifying the satellites in the file,
% then the code and carrier for each of the satellites are tracked, storing
% the 1msec accumulations.  After processing all satellites in the 37 sec
% data block, then postNavigation is called. It calculates pseudoranges
% and attempts a position solutions. At the end plots are made for that
% block of data.

%--------------------------------------------------------------------------
%                           SoftGNSS v3.0 GLONASS version
% 
% Copyright (C) Darius Plausinaitis
% Written by Darius Plausinaitis, Dennis M. Akos
% Some ideas by Dennis M. Akos
% Updated and converted to scilab 5.3.0 by Artyom Gavrilov
%--------------------------------------------------------------------------
%This program is free software; you can redistribute it and/or
%modify it under the terms of the GNU General Public License
%as published by the Free Software Foundation; either version 2
%of the License, or (at your option) any later version.
%
%This program is distributed in the hope that it will be useful,
%but WITHOUT ANY WARRANTY; without even the implied warranty of
%MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%GNU General Public License for more details.
%
%You should have received a copy of the GNU General Public License
%along with this program; if not, write to the Free Software
%Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
%USA.
%--------------------------------------------------------------------------

%                         THE SCRIPT "RECIPE"
%
% The purpose of this script is to combine all parts of the software
% receiver.
%
% 1.1) Open the data file for the processing and seek to desired point.
%
% 2.1) Acquire satellites
%
% 3.1) Initialize channels (preRun.m).
% 3.2) Pass the channel structure and the file identifier to the tracking
% function. It will read and process the data. The tracking results are
% stored in the trackResults structure. The results can be accessed this
% way (the results are stored each millisecond):
% trackResults(channelNumber).XXX(fromMillisecond : toMillisecond), where
% XXX is a field name of the result (e.g. I_P, codePhase etc.)
%
% 4) Pass tracking results to the navigation solution function. It will
% decode navigation messages, find satellite positions, measure
% pseudoranges and find receiver position.
%
% 5) Plot the results.

% Initialization =========================================================
disp ('Starting processing...');

[fid, message] = fopen(settings.fileName, 'rb');

%Initialize the multiplier to adjust for the data type
if (settings.fileType==1) 
  dataAdaptCoeff=1;
else
  dataAdaptCoeff=2;
end

%If success, then process the data
if (fid > 0)
  
  % Move the starting point of processing. Can be used to start the
  % signal processing at any point in the data record (e.g. good for long
  % records or for signal processing in blocks).
  fseek(fid, dataAdaptCoeff*settings.skipNumberOfBytes, 'bof'); 
  
% Acquisition ============================================================
  
  % Do acquisition if it is not disabled in settings or if the variable
  % acqResults does not exist.
  if ((settings.skipAcquisition == 0) | ~exist('acqResults', 'var'))
    
    % Find number of samples per spreading code
    samplesPerCode = round(settings.samplingFreq / ...
                           (settings.codeFreqBasis / settings.codeLength));
    
    % Read data for acquisition. 11ms of signal are needed for the fine
    % frequency estimation
    
    data  = fread(fid, dataAdaptCoeff*(settings.acqCohIntegration*2 + 1)*...
                 samplesPerCode, settings.dataType)';
    
    if (dataAdaptCoeff==2)
        data1=data(1:2:end);
        data2=data(2:2:end);
        if (settings.switchIQ == 1) then
            data=data2 + i.*data1;
        else
            data=data1 + i.*data2;
        end
    end
    
    %--- Do the acquisition -------------------------------------------
    disp('   Acquiring satellites...');
    acqResults = acquisition(data, settings);
    
    plotAcquisition(acqResults);
  end
  
% Initialize channels and prepare for the run ============================
  
  % Start further processing only if a GNSS signal was acquired (the
  % field FREQUENCY will be set to 0 for all not acquired signals)
  if (any(acqResults.carrFreq))
    channel = preRun(acqResults, settings);
    showChannelStatus(channel, settings);
  else
    % No satellites to track, exit
    disp('No GNSS signals detected, signal processing finished.\n');
    trackResults = [];
    return;
  end
  
% Track the signal =======================================================
  startTime = now;
    disp (['   Tracking started at ', datestr(startTime)]);
  
  % Process all channels for given data block
  [trackResults, channel] = tracking(fid, channel, settings);
  
  % Close the data file
  fclose(fid);
  
  disp(['   Tracking is over (elapsed time ', ...
                                        datestr(now - startTime, 13), ')'])     
  
  % Auto save the acquisition & tracking results to a file to allow
  % running the positioning solution afterwards.
  disp('   Saving Acq & Tracking results to file trackingResults.mat')
  save('trackingResults.mat', 'trackResults', 'settings', 'acqResults', 'channel');
  
% Calculate navigation solutions =========================================
  disp('   Calculating navigation solutions...');
  navSolutions = postNavigation(trackResults, settings);
  disp('   Processing is complete for this data block');
  
% Plot all results ===================================================
  disp('   Ploting results...');
  if settings.plotTracking
    plotTracking(1:settings.numberOfChannels, trackResults, settings);
  end
  
  plotNavigation(navSolutions, settings);
  
  disp('Post processing of the signal is over.');
  
else
  % Error while opening the data file.
  error('Unable to read file %s: %s.', settings.fileName, message);
end % if (fid > 0)
